1. Technical Field
The present disclosure relates to electron emitters and, more particularly, to a thermal electron emitter based on carbon nanotubes.
2. Discussion of Related Art
Thermal electron emission devices are widely applied in gas lasers, arc-welders, plasma-cutters, electron microscopes, x-ray generators, and the like. Conventional thermal electron emission devices are constructed by forming an electron emissive layer made of alkaline earth metal oxide on a base. The alkaline earth metal oxide includes BaO, SrO, CaO, or a mixture thereof. The base is made of an alloy including at least one of Ni, Mg, W, Al and the like. When thermal electron emission devices are heated to a temperature of about 800° C., electrons are emitted from the thermal electron emission source. Since the electron emissive layer is formed on the surface of the base, an interface layer is formed between the base and the electron emissive layer. Therefore, the electron emissive alkaline earth metal oxide is easy to split off from the base. Further, thermal electron emission devices are less stable because alkaline earth metal oxide is easy to vaporize at high temperatures. Consequently, the lifespan of the electron emission device tends to be low.
What is needed, therefore, is a thermal electron emission device, which has stable and high electron emission efficiency, as well as a great mechanical durability.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one embodiment of the present thermal electron emission device, in at least one form, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner.